Exemplary embodiments relate to a semiconductor memory device and, more particularly, to a semiconductor memory device performing a repair operation.
If defective memory cells are found in fabricating a semiconductor memory device, the semiconductor memory device may be treated as a bad product, and a reduction in the yield of the semiconductor memory devices may result if the entire semiconductor memory device is discarded due to the presence of few defective memory cells.
Therefore, semiconductor memory devices are further provided with a reserved unit memory cell, and a defective unit memory cell is replaced with the reserved unit memory cell so that a semiconductor memory device can be used despite having the defective unit memory cell.
If a defective column exists in a semiconductor memory device, a column repair operation may be performed in order to replace the defective column with a redundancy column.
Meanwhile, in order to increase the data input/output (I/O) speed, a wide I/O method in which memory arrays are classified into a plurality of groups by increasing the number of internal data lines may be used. According to the wide I/O method, since a redundancy column may not be used among the groups even though the same data line is shared by the groups, the repair operation may be limited in some groups when redundancy columns are not sufficient.